Rat eradication is a highly effective tool for conserving biodiversity, but one that requires considerable planning eff ort, a high level of precision during implementation and carries no guarantee of success. Overall, rates of success are generally high but lower for tropical islands where most biodiversity is at risk. We completed a qualitative comparative review on four successful and four unsuccessful tropical rat eradication projects to better understand the factors influencing the success of tropical rat eradications and shed light on how the risk of future failures can be minimised.

Rodents are a key pest to agricultural and rural island communities of the South Pacific, but there is limited information of their impact on the crops and livelihoods of small-scale farmers. The rodent pest community is known, but the type and scales of damage to different crops on different islands are unknown. Knowledge about rodent pest management in other geographical regions may not be directly transferable to the Pacific region. Many studies on islands have largely focussed on the eradication of rodents from uninhabited islands for conservation benefits.

Pacilic island countries are particularly vulnerable to the effects of invasive species. After habitat destruction or modification, invasive species are responsible for more species extinctions than any other cause. Further, the rate of extinction of native species has been higher on islands than anywhere else in the world. Invasive species have also degraded native ecosystems.

Global biodiversity loss is disproportionately rapid on islands, where invasive species are a major driver of extinctions. To inform conservation planning aimed at preventing extinctions, we identify the distribution and biogeographic patterns of highly threatened terrestrial vertebrates (classified by the International Union for Conservation of Nature) and invasive vertebrates on ~465,000 islands worldwide by conducting a comprehensive literature review and interviews with more than 500 experts.

While eradication projects on large islands require substantial funding and a high level of technical and logistical support, projects on small islands are much simpler and can achieve success with much less funding and outside assistance. The Pacific has thousands of such islands that can contribute to significant biodiversity outcomes. The purpose of this guide is to assist the practitioner in removing invasive rodents from small islands (less than 20 hectares) where access to all parts of the island is possible.

National or Territory Invasive Species Strategies and Action Plans (NISSAP) are a critical document to ensure invasive species management is coordinated within a country or territory and that the different sectors involved with invasive species management are working together toward the same goals. NISSAP are essential to show political will for managing invasive species and are looked upon favourably by funding bodies.